---
title: "Intoxication Defense"
type: Legal Rule
source: https://casebriefly.com/legal-rules/intoxication-defense
---

# Intoxication Defense

Voluntary intoxication may negate specific intent but is no defense to general intent crimes. Involuntary intoxication is treated like insanity and can serve as a complete defense if it renders the defendant unable to understand the nature of their act.

## Definition

The intoxication defense distinguishes between voluntary and involuntary intoxication, applying different rules to each. Voluntary intoxication, where the defendant knowingly consumed alcohol or drugs, is available only as a defense to specific intent crimes. It may negate the mens rea element by showing the defendant was so intoxicated that they could not form the specific intent required for the offense. However, voluntary intoxication is never a defense to general intent crimes, crimes requiring recklessness or negligence, or strict liability offenses.

Under the Model Penal Code, voluntary intoxication can negate purpose or knowledge but cannot negate recklessness. A defendant who is unaware of a risk due to voluntary intoxication is treated as if they were aware of the risk, because the MPC considers self-induced intoxication itself as reckless behavior. This effectively means voluntary intoxication can reduce a first-degree murder charge (requiring premeditation) to second-degree murder but cannot provide a complete defense to any crime requiring recklessness.

Involuntary intoxication receives much more favorable treatment. It occurs when the defendant unknowingly ingested an intoxicating substance, was forced to consume it, had an unexpected reaction to prescribed medication, or became intoxicated through pathological causes. Involuntary intoxication is treated like the insanity defense: if the intoxication rendered the defendant unable to understand the nature of their actions or to distinguish right from wrong, it is a complete defense to any crime. The distinction between voluntary and involuntary intoxication is therefore critical and often dispositive on the exam.

## Elements

- Determine whether intoxication was voluntary or involuntary
- Voluntary intoxication: may negate specific intent but not general intent
- Voluntary intoxication under MPC: may negate purpose or knowledge but not recklessness
- Involuntary intoxication: treated like insanity and may be a complete defense to any crime
- The defendant must show intoxication actually prevented them from forming the required mental state

## Key Case

Montana v. Egelhoff, 518 U.S. 37 (1996)

## Landmark Cases

| Name | Citation | Significance |
| --- | --- | --- |
| Montana v. Egelhoff | 518 U.S. 37 (1996) | Upheld a Montana statute prohibiting consideration of voluntary intoxication to negate mens rea, finding no due process violation |
| People v. Hood | 1 Cal. 3d 444 (1969) | Held that voluntary intoxication is a defense to specific intent crimes but not to general intent crimes like assault |
| Director of Public Prosecutions v. Majewski | [1977] AC 443 (HL) | Influential English case establishing the specific intent/general intent distinction for intoxication defenses |

## Exam Tips

- First classify the crime as specific intent or general intent (or identify the MPC mental state); this determines whether voluntary intoxication is relevant
- Under the MPC, voluntary intoxication can negate purpose and knowledge but never recklessness or negligence
- Involuntary intoxication is analyzed like insanity; apply the applicable insanity test
- Remember that some states (like Montana) have eliminated the voluntary intoxication defense entirely

## Common Mistakes

- Assuming voluntary intoxication is a defense to all crimes; it only applies to specific intent crimes (or purpose/knowledge under MPC)
- Forgetting to distinguish voluntary from involuntary intoxication; involuntary intoxication is treated like insanity and is far more powerful
- Confusing intoxication with insanity; chronic substance abuse that causes a permanent mental condition may qualify as insanity, but mere intoxication does not

## Mnemonic Or Memory Aid

"Voluntary = Specific only; Involuntary = Insanity equivalent" -- voluntary intoxication negates only specific intent; involuntary intoxication acts like a full insanity defense

## Related Rules

- mens-rea-mental-states
- insanity-defense-mnaghten
- insanity-defense-model-penal-code
- homicide-degrees-of-murder

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Source: [Intoxication Defense — CaseBriefly](https://casebriefly.com/legal-rules/intoxication-defense)